Heretofore, various attempts have been made to achieve a wrench whose jaws could be locked readily in any desired position. Such previous attempts have proved to be significantly less than successful, especially with respect to ease of operation, simplicity of mechanism, ability to operate by the use of one hand only, and the ability to hold and maintain the desired adjusted position.
Without dwelling inordinately on the animadversions of the prior art attempts, there is nevertheless set forth hereinbelow a terse and cursory discussion of several exemplary prior art attempts.
Anderson U.S. Pat. No. 1,846,380, entitled "WRENCH", discloses a wrench wherein one end of the worm shaft functions as a push-to-adjust button. Pushing such button overcomes the spring tension which holds a key or locking member 23 within one of the grooves 28 in an end of the worm gear, and thereby allows the worm gear to rotate. The disclosed Anderson wrench appears to have a single scale 29 which is divided into fractions of an inch to indicate the distance between the opposing wrench jaws.
In contrast to the present invention, the jaws of the Anderson wrench are not capable of being locked in an infinite number of positions. Rather, the Anderson jaws may only be locked in a position where the key or locking member 23 is able to fit within or engage in associated group 28 in the worm gear end.
Truby U.S. Pat. No. 2,385,660, entitled "LOCKING WRENCH" discloses an infinitely-variable adjustable wrench which is provided with a shaft which is mounted in a fixed position upon which a worm gear is normally free to rotate. One end of the shaft is internally threaded to receive a knurled-head thumbscrew. Turning the thumbscrew into the shaft forces a ball bearing against the inside diameter of the worm gear, jamming the worm gear against the jaw rack and forcing the worm gear into a cocked position. The worm gear is spring-loaded against one side of the opening.
In contrast to the present invention, the Truby worm gear is not truly free to turn in the unlocked position, because it is spring-loaded against one end of the adjusting opening, and the shaft is not free to turn. Furthermore, there is no way to unlock and lock the wrench with the hand that is holding the wrench, and there is no preset locked position nor a preset unlocked position.
Johnson U.S. Pat. No. 2,719,449, entitled "OPEN END WRENCH LOCKING MEANS", discloses a wrench locking means wherein there is mounted an adjusting screw or worm upon a slidable shaft which is adapted to be held in either of two adjustable limiting positions by spring means which also function to hold the wrench parts in assembled relation. The Johnson worm 18 has a bore therethrough which, for at least a portion of its length, is in the shape of a polygon having a number of sides which is an integer multiple of the number of sides of the shaft 19 to provide a non-rotative engagement therewith, and a second portion 25 of the bore is of an enlarged diameter to permit rotatable fit across the corners of the polygonal shaft.
In contrast to the Johnson disclosure, the present invention provides a shaft and a worm which are connected together as an integral unit so as to rotate as an integral unit or to be locked together as an integral unit and to prevent any slidable movement between the shaft and the worm under all conditions and at all times.
Barnes U.S. Pat. No. 2,729,999, entitled "ADJUSTING AND LOCKING MEANS FOR SLIDABLE JAW WRENCH", discloses a wrench with a shaft having hexagonal portions that may be engaged with hexagonal portions of a shaft bore in the wrench body.
In contrast to the present invention, the jaws of the Barnes wrench can be adjusted only to discrete positions where a hexagonal shaft and splined hole are in alignment, and is not useable where, for example, both English and metric bolt heads or nuts must be closely gripped, or where a non-symmetrical, non-standard or irregular surface must be closely and tightly gripped and turned.
Heuser U.S. Pat. No. 2,817,259, entitled "ADJUSTMENT LOCKING MEANS FOR ADJUSTABLE JAW WRENCHES", discloses a wrench having a shaft with hexagonal ends slidable in hexagonal holes in the wrench body. The shaft engages with an internally-splined portion of the worm gear in locked position. The Heuser device uses a simple rubber housing to serve to retain the shaft in the wrench body.
Again, in contrast to the present invention, the jaws of the Heuser wrench can be locked only in a discrete position where the hexagonal shaft and the splined worm gear bore are in alignment. In other words, the jaws of the Heuser wrench cannot be locked in an infinite number of positions.
The present invention provides an improved wrench which is superior to the devices discussed hereinabove, and also which has beneficial advantages and features mentioned hereinbelow.